The Joonics believe in an absolute commitment to nonviolence. Each living thing you kill or cause the death of is punished in the next life, which manifests as years spent in a divine prison cell. Each HD of a creature you kill is a year, but even stepping on a bug or eating meat could add a few hours or days to your punishment. Eating carrion is not considered a sin, but buying meat from a farmer increases the demand for meat ever so slightly, causing more death, so you're guilty by some infinitesimal fraction. Causing or demanding someone's death indirectly is still considered guilt; a jealous queen who convinces her husband to hire and assassin to kill someone would mean that all of them would be guilty, but the exact amount of time each gains is variable. If the assassin used poisons he would be a little less guilty then if he used a knife, and so on. Warlords and Rulers of any kind easily stack up thousands, or even millions of years of punishment. Joonics abhor power for this reason.
The most common belief is that intelligent mortals receive 188 healthy years in the next life that they may exist. If their time of punishment extends beyond this, they are forced to endure it however long it is and at the moment it ends, they cease to exist. The time of punishment lasts for all the killing and violence they caused, and you are trapped in a small dirt cell with a window too high to reach, a simple cot, a hole in the floor, and are fed a single bowl of rice each day. Killing yourself is not possible, and simply adds a day to your time. Escape is also not possible.
If their 188 years is less then this jail sentence, that means they may leave the divine prison once their time is up and enjoy a short existence of bliss and joy before ceasing to exist. The Joonic religion is often combined with other religions and the “real” afterlife is spent after the Joonic one. Strict followers of Joon know better, and understand that whatever lies beyond is not as important as the divine jail. The Joonic afterlife outside of the jail cell is actually very nice, and includes a lake whose waters cause a feeling of total bliss in those who float on them, clouds which let you experience the good thoughts of all sleeping creatures on earth, and gardens with introspective fruits. But joy is fleeting, and every moment spent in your jail cell is time not spent in heaven.
In practice, the Joonics live by an absolute code of nonviolence, even in self defense. They are pretty much all vegetarians. In practice, their faith involves a lot of self discipline, constant care in their actions, and periods of self imprisonment and punishment. Spending a day in a prison willingly in your real life is equal to paying off one day of prison in the afterlife, so many Joonics are willingly imprisoned. More casual followers can put bars on their windows and eat nothing but rice to gain a tiny amount of sympathetic time off their prison sentence.
Is it possible to play as a Joonic adventurer? Absolutely. Joonic adventures will mostly play support classes, like Sages, and use indirect or accidental means of killing. With enough steps between you and the target, you may be able to whittle down the amount of time you get from killing them to almost nothing. Making your opponent fall on your sword is obviously a little less violent then stabbing them, and spreading grease on the floor to make them slip up themselves is even a little less violent, since it's their fault for tripping. Joonic's would probably receive a free jail at name level.